Submerged resistor electric induction furnace



Sept. 23, 1947. M. TAMA SUBIERGED RESISTOR ELECTRIC INDUCTION FURNACE Fiied lay 24, 1945 INVENTOR.

Patented Sept. 23, 1947 SUBMERGED RESISTOR ELECTRIC INDUCTION FURNACE Manuel Tania, Mortisville, Pa.

Application May 24, 1945, Serial No. 595597 The invention relates to induction iumaces of the submerged resistor type, and more particularly to i'urnaces of'this type for melting light metais and alloys. v

A difllcult problem .in the operation of this type induction furnaces resides therein that the impurities and the slags resulting from the melting procedure form deposits in the melting channels, which deposits gradually reduce the working area of the channels and eventually clog them up entirely.

Further-more, the slags attack and gradually destroy the walls of the melting channels.

In consequence thereot frequent interruptions and shutdowns of the iurnace operation result.

It is an object of the invention to provide a submerged resistor type lnduction furnace which will allow the removal of the slag and other impurities while maintaining the same filled and insoi'ar without interrupting its operation.

A further object ot the invention is the provision ot melting channels in a furnace of the aforesaid type which may be thoroughly and easily cleaned while the iurnace is working and contains its Iull charge of molten metal. v

Another purpose is to provide a furnace of the type described in which the impurities can collect at a' spot provided for them free from the path o! the normal metal flow and from which they can be removed while the furnace is filled with the charge.

A further purpose is to provide a furnace of the type described in which the metal, as it is poured. has a scouring action on the walls of the melting channels.

The construction and operation of the furnace according to the present invention will best be understood by referring to the drawings wherein two modifications o! the urnace have been shown by way of example, this being deemed sufiicient for disclosure of the invention as claimed.

In the drawings,

Flg. 1 is a vertical sectional elevation of a furnace embodying the principal features of my invention taken on line l--I of Fig. 2,

Fig. 2 is a sectional horizontal elevation of the !urnace taken on line 2-2 of Fig. 1, and

Fle. 3 is a sectional horizontal elevation similar to that of Fig. 2 showing a furnace which is provided with two melting ducts.

The furnace is provided with two hearths or chambers i and 2 which are connected by three melting channels I, l. 5. The iurnace and its parts are encased in a housing n which is lined with aretractory l I.

9 Claims. (Cl. 13-29) Transformer assemblies comprising iron cores i and primary coils 8 are threaded through secondary loops formed by the melting channels and the bottom sections of the two hearths and are designed to induce current into the molten metal which is filled into the hearths up to level L. The transformer assemblies are insulated from the refractory lining li by asbestos cement sleeves !2.

The two primary coils may -be Scott connected to a standard three phase powersource or they may be connected to a single phase supply. For a single phase design only one transformer assembly and two connecting ducts or channels 3, 4 would be required, as shown in Fig. 3.

The bottom of the higher chamber 2 is located well above the bottom of the lower chamber or hearth l and the melting channels 3, l, 5 into which the heating current is induced are-located in such a manner that any impurities which fall to the bottom of chamber 2 are conducted into the channels 3, 4, 5 and from these channels into the bottom section of hearth I. For this purpose the bottom of chamber 2 is slanting in a direction towards chamber I. .A recess 1 is provided in the bottom section of chamber l and below the entry of the melting channels in which lmpurities and slags may be allowed' to collect. Cleaning openings !4 are provided in the outside wall !3 of hearth 2 on the side opposite to the entering points of the melting channels.

The strongly inclined position of the melting channels forms an important feature in the construction of induction furnaces of the submerged resistor type and signifies the great progress created by this invention. This Construction is a perfect safeguard against contamination of the melting channels and of the molten charge. It actually and efiiciently solves the difficult problem of slag removal while the furnace remains filled with the charge. The cleaning of the furnace during operation is further improved by the arrangement of recess 1 at the bottom oi hearth I, as explaincd in a later part of this speciiication.

As apparent from the drawings, the melting channels are inclined under such an angle, that the extension of an axis a: extending parallel to the direction of the inclination strikes the outside wall !3 of hearth 2 at a point which is located adjacent to its upper edge and at least above its middle height( Therefore, straight cleaning tools can be easily inserted through openings ll into the metal melting channels and the slag removed therefrom 3 without necessitating an interruption prevents the deposition of slags along the channel walls.

melting channels in that chamber. flows down through the channels and rises in lower chamber l. As the power is turned on, the metal in the channels becomes heated and now metal can be added in the upper chamber 2,

as forms on its surface in the smaller chanber.

molten charge.

Cleaning of the ducts is necessary when nonmetallic pieces become lodged in them;

creases the resistance and improves the overall power factor ot the furnace. When scaled furnaces of a. former customary and of the present design 'were compared, it was found that the power factor of the former was but 35 per cent as compared to the new design. The i'umce klowatt, 60 cycle size.

stray magnetic eld.

The straight melting channels 3, 4, 5 and the In respects other than as noted in this specification, the present furnace furnaces.

I claim:

1. A submerged resistor type inductio Iurnace oi' separate hearths having introduction of cleaning tools from the outside wall of the iu-nace and above the level oi the molten charge.

3. A suhmerged resistor type induction iurnace eonprsing a plurality of separate hearths having different levels. at least two subthe inside of the ing its bottom at a higher level with the inside of me bottom section of another hearth having its bottom at a lower level, at least one transthreading the secondary loop melting channels, at least one cleaning opening in the outside wall of the hearth having its bottom at a higher level, said straight melting channeis being inclined at an angle to permit the introduction oi cleaning tools through said opening above the level of the molten charge.

4. A suhmerged resistor type induction fumace comp-lsing a plurality oi separate hearths having their bottom at different levels, at least two substantillv straight meting channels connecting the inside oi the bottom section of a nearth having its bottom at a higher level with the inside oi the bottom section of another hearth having its bottom at a lower level, at least one transio-mer asenbly threadin the secondary loop io-ned by the said melting channels, apertures in the outside wall of the hearth having its bottn at a higher level, said apertures being located above halt the height of said hearth, said straight melung channeis being inclined at an angle to the introduction of cleaning tools through said ;permes into said channels above the level of th molten chrge.

5. A submerged rsistor type induction iurnace camp-!sing aplurality oi 'separate hearths having their bottom at diiierent levels. at least two substntially straight melting ehannels connecting the bottmn section oi' a hearth having its bottom athigherlevelwiththebottomsection oi another hearth having its bottom at a lower level, at least one transfer-mer assembly threading the seeodar! loop toi-med by the said melting channeis. said straight melting channels being inclined at such n angle that a center line extending throughsaidchannelsinthedirectioniroma heu-th with a lower bottom to a hearth with a bottn strike: the outside wall oi said letter hearth at above half its height, apertures in the outside vall of said latter hearth located atabovehlitheheightoisaidhearthtopermit the introductio of cleaning tools through said perires into said straight channels above the level of the molten eharge.

6. A reistor type induction iumace eonrlsing a hu-aliu or separate hear-ths havi their bottom: ai'. diilerent levels. at least two subtntili! straight melflng channel: connecting thebotwmsectionoiahearthhaving its bottom at higher level with the bottom section oi another hertl having its bottom at a lower level. tleatonetransiorme' ly threading the eeonda'! loop iormed by aid meltingchannes, said ::night melting channels being inclined at anangleoibmtbetweenw to 50' topermit the introdeflou oi cleaning tools irom the outside ortbeturneeandabovetheevei oi the molten M '1. A reshto! type inductiol filmu& emm-Hag a plurality oi separate hearths having thdrbottoatdifleratlevitloattwoubv the said melting channels,

stantially straight melting Channels connecting the bottom section of a hearth having its bottom at a lower level with the bottom section of another hearth having its bottom at a higher level, a groove at the bottom of the health having its bottom at a lower level, at least one transformer assembly threading the secondary loop formed by said straight melting channels being inclined at an angle to permit the introduction oi cleaning tools from the outside wall of the furnace and above the level oi the molten charge.

8. A submerged resistor type induction furnace comprising a pl i ty of separate hearths having their bottoms at diflerent levels at least two substantially straight melting Channels connectin the bottom section oi a hearth having its bottom at a higher level with the bottom section of another hearth having its bottom at a lower level, a groove at the bottom of the hearth having its bottom at a lower level, at least one transi'ormer assemby threading the secondary loop formed by the said melting channels, apertures in the outside wall ot a hearth having its bottom at a higher level, said straight melting channels being inclined at an angle to permit the introduction of cleaning tools in said channels and said bottom groove from the outside wall of the iurnace and above the level of the molten charge.

9. A submerged resistor type induction furnace i comprising a plurality of separate hearths havin their bottoms at different levels, at least two substantially straight melting channels connecting the bottom section of a hearth having its bottom at a higher level with the bottom' section of another hearth having its bottom section at a lower level, at least one ing'the secondarv loop iormed by the said melting channels, said straight melting channels being inclined at an angle to permit the introduction of cleaning tools from the outside of the tumace and above the level oi the molten charge, while keeping the channels !uu of molten metal.

MANUEL TAMA.

narrmvcns crm The following reierences are of record in the me of this patent:

UNITED STATES PATENTS Number Name Date 1405556 Hering 1 Aug. 4', 1914 1402373 Hering Dec. '1, 1915 1,313,2'i4 DeBarros Aug. 19, 1919 1,599,161 Brayton, Jr. Sept. 7, 1926 1,648,'l0'l Weed Nov. 8, 1927 1370562 Russ July 15, 1930 1971868 case Bept. 11, 1934 2016316 Wyatt Apr. 8, 1937 &286.024 `Tamaet al June 9, 1942 FOREIGN PATENTS Number Country Date 138504 Great Britain Dec. 23, 1920 514.357 Germany Dec. 11, 1930 842556 Germany Mar. 8, 1937 4,469 Sweden Mar. 8, 1892 109.793 Sweden Feb. 15, 1944 OTEER REFEBENCES Metali-Wirtschaft Wissenschaft Technik," Feb. 5. 1948. pages 71. '12.

transiormer assembly thread- 

